close

Вход

Забыли?

вход по аккаунту

?

JP2008236781

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2008236781
An excellent ultrasonic transducer is provided by combining two components. An ultrasonic
transducer with a sleeve has a two-part head mass, which comprises a threaded sleeve and an
outer housing, which are made of different materials . The threaded sleeve is preferably made of
a material such as titanium that provides excellent thread strength for screwing with the
compression bolt 24, while the outer housing provides excellent heat sinking capability. It is
desirable to be made of aluminum, ceramic, or other metal or non-metal material in order to
exert a superior vibration energy transfer function. [Selected figure] Figure 1
Ultrasonic transducer with sleeve
[0001]
The present invention relates generally to ultrasonic generators, ultrasonic transducers, and
ultrasonic converters, and more particularly to ultrasonic transducers or ultrasonic converters
having a two-part head mass or front driver. .
[0002]
Here, one part of the head mass provides a perfect thread and the other part provides an
excellent sound transmission and / or heat transfer property.
[0003]
A typical prior art stacked ultrasound transducer or transducer 10, 12 is shown in FIGS.
04-05-2019
1
Both transducers 10, 12 have a plurality of PZTs 14 (piezoelectric crystals or transducers) which
are annular in shape and are referred to as the tail mass or back driver 16 and the head mass or
front driver It is disposed between the portions designated 18 (FIG. 1) or 20 (FIG. 2).
A bolt 22 for holding the PZTs 14 between the head mass and the tail mass and compressing the
PZTs 14 is screwed into the internal threads of the head mass 18 or 20. The insulating sleeve 23
electrically isolates the PZTs 14 from the bolts 22 and the electrical contacts 25 are electrically
connected to the PZTs 14. The threaded extension 24 allows the converter to be attached to a
booster or horn (not shown) used in ultrasonic welding and similar applications. PZTs function in
the thickness direction. This means that the PZTs expand mainly in the direction of the central
axis 26 of the transducer and come into contact with each other. The head masses 18, 20 are
tapered to amplify the amplitude of the PZTs 14 oscillations.
[0004]
In FIG. 1, the head mass 18 is made of a single material such as aluminum or titanium. Aluminum
has the advantage of having a high heat capacity and acting as a heat sink to dissipate heat from
the PZTs. However, aluminum is a relatively soft metal and the threads needed to hold the bolt
22 and threaded extension 24 are weak. Titanium has excellent properties compared to
aluminum, that is, the material strength and the strength of the threaded portion are high, but it
is a material having a smaller heat capacity and less effective heat absorption than aluminum.
[0005]
In the transducer 12 shown in FIG. 2, titanium is used in place of aluminum for the threaded
portion of the head mass. The two-piece head mass 20 consists of a base portion 28 made of
aluminum followed by PZTs 14 and a tip portion 30 made of titanium, and inside the tip portion
30 a bolt 22 is threaded A screw threading with the extension 24 is cut. The drawback of using
such a two-part head mass design is that due to the junction of the two materials, it reduces the
amplitude gain at the tapered head mass portion, which causes the PZTs 14 to boost or It
interferes with the transmission of ultrasonic vibrational energy to the horn so that it can not
perform as well as a single head mass.
04-05-2019
2
[0006]
In another application described above, the ultrasound transducer is directly attached to the
surface to which ultrasonic vibrational energy is to be transmitted. For example, it can be
attached to the outer surface of a container filled with cleaning solution and containing the
cleaning material to be ultrasonically cleaned. In such applications, the ultrasound transducer
can be adhesively bonded to the container surface. However, if the material of the container and
the material of the head mass are different, the coefficient of thermal expansion may be different,
and the adhesive joint may be broken. If the cleaning vessel is made of quartz and the head mass
of the transducer is made of aluminum, the coefficients of thermal expansion will differ
considerably.
[0007]
SUMMARY OF THE INVENTION The present invention is a sleeved ultrasonic transducer having a
threaded sleeve on one portion of the head mass and an outer housing made of a different
material on the other portion of the head mass. Pertain to. Because the head mass consists of two
parts, it can be made of different materials and can be optimized to have different properties and
functions. The outer housing is preferably made of aluminum or ceramic which can enhance heat
sink performance and / or vibration energy transfer characteristics, while the threaded sleeve
has bolts and threaded extensions and threads It is desirable to use metals such as titanium that
can be combined and have excellent screw strength. A good combination of the two components
can provide an excellent ultrasound transducer.
[0008]
Furthermore, the ultrasound transducer according to the invention comprises one or more discshaped piezoelectric crystals, each piezoelectric crystal having an axial hole. A tail mass is
disposed on one side of the piezoelectric crystal, and the tail mass has an axial hole. A head mass
is disposed on the side opposite to the tail mass of the piezoelectric crystal, and the head mass
has an axially threaded axial bore therein.
[0009]
04-05-2019
3
The axial holes in each piezoelectric crystal and the threaded bolts located in the axial holes in
the tail mass and head mass are internally threaded in the head mass and in the axial direction Is
screwed into the hole of. The bolt then compresses the piezoelectric crystal between the tail mass
and the head mass. The head mass consists of two parts made of different materials, one is a
sleeve with an internally threaded axial hole, with a reduced diameter part, the other one An
outer housing located outside the reduced diameter portion of the threaded sleeve.
[0010]
Preferably, the threaded sleeve and the outer housing are in contact in a plane perpendicular to
the axis of the transducer. Furthermore, it is desirable for the outer diameter of the reduced
diameter portion of the threaded sleeve to be equal to the inner diameter of the one or more
piezoelectric crystals.
[0011]
The features and advantages described herein are not all inclusive and, in particular, those skilled
in the art will appreciate many additional features and advantages from the description of the
drawings, the specification, and the claims. Will. Furthermore, the words used in the specification
are mainly used for the purpose of easy-to-read explanation, and are not used to describe or limit
the subject matter of the invention. In order to determine the subject of the invention, it is
necessary to make a judgment based on the description of the claims. For example, the terms
transducer, converter, and generator are used herein as interchangeable terms to refer to devices
that generate ultrasonic vibrations in response to electrical drive signals. The term piezoelectric
crystal is used as a term compatible with the term piezoelectric transducer or PZT. Further, the
terms head mass and front driver are interchangeable terms used to refer to the portion of the
transducer (or converter or generator) that transmits ultrasonic vibrational energy to the object.
Similarly, the terms tail mass and back driver are on the opposite side of the head mass (or front
driver), and the part of the transducer (or converter or generator) to balance the vibration of the
piezoelectric crystal It is a compatible term used to call.
[0012]
For the purpose of illustration, the figures show various preferred embodiments according to the
present invention. Based on the following discussion, it is easy for a person skilled in the art to
04-05-2019
4
think of other embodiments of the structures and methods described herein without departing
from the essence of the present invention described herein.
[0013]
As shown in FIGS. 3-6, the sleeved ultrasonic transducer 40 according to the present invention
has an internally threaded sleeve 44 made of one material and corresponding holes made of
another material A head mass 42 is provided which consists of two parts consisting of an outer
housing. The threaded sleeve 44 is preferably made of titanium or other metal so that the
strength of the threads is sufficient. In addition, the outer housing needs to have appropriate heat
transfer, thermal expansion properties, and / or be able to efficiently transfer the vibrational
energy generated by the PZTs 14 (piezoelectric transducer or crystal). It is desirable that it be
made of aluminum, other metals, ceramics or other non-metallic materials with appropriate
thermal and / or acoustical properties.
[0014]
The sleeve 44 is cut with a screw 48 that engages with the screw of the bolt 22 and the screw of
the extension 24. The outer housing 46 is provided with a flat upper surface 50 in contact with
the PZT stack and a counterbore hole 52 which nests with the reduced diameter portion 54 of
the threaded sleeve 44. The outer housing 46 is provided with a flat lower surface 56
perpendicular to the axis of the transducer and against the shoulder 58 of the threaded sleeve
44. The PZTs 14 are compressed by the upper surface 50 of the outer housing 46 by the bolt 22
and the lower surface 56 is compressed by the shoulder 58 of the threaded sleeve 44. Axial
vibrations generated from the PZTs 14 pass through the outer housing 46 and are threaded
through the contact surface of the lower surface 56 of the outer housing 46 with the shoulder 58
of the threaded sleeve 44. Propagate to
[0015]
The lower surface 56 of the outer housing 46 is preferably located at the cylindrical portion 60
of the head mass rather than at the tapered portion 62. The gain of the vibration amplitude at the
head mass will be fully developed at the tapered portion 62 so that the vibration at the
cylindrical portion 60 is an axial vibration. It faces the connecting portion of the two halves of
the head mass, i.e., the shoulder 58, in order to allow axial vibrations to propagate efficiently
04-05-2019
5
from the outer housing 46 to the threaded sleeve 44. An end face of the lower side surface 56 is
provided at the position of the cylindrical portion. The outer diameter of the tapered portion 54
of the threaded sleeve 44 is preferably substantially equal to the inner diameter of the PZTs 14.
Compared to the prior art ultrasonic transducer 12 (see FIG. 2) having a bifurcated head mass
20, the invention with an aluminum outer housing 46 and a titanium threaded sleeve 44 In the
case of the sleeved ultrasonic transducer 40 according to the invention, the aluminum portion is
increased to enhance the heat sink characteristics, and efficient vibration propagation is
performed between the two parts made of aluminum and titanium. It is supposed to be. While the
minimum impedance of the superior sleeved transducer 40 of the present invention shown in
FIG. 8 is 4.18 ohms, as can be seen from FIG. 7, the prior art transducer 12 has a minimum of
11.24 ohms. It has an impedance.
[0016]
In comparison to the prior art single head mass ultrasonic transducer 10 (see FIG. 1), the
invention has an aluminum outer housing 46 and a titanium threaded sleeve 44 according to the
invention In the case of such a sleeved ultrasound transducer 40, having a thread strength higher
than the thread strength of the head mass made entirely of aluminum and achieving a heat sink
characteristic greater than the head mass made entirely of titanium. Can. The combination of the
aluminum outer housing 46 and the titanium threaded sleeve 44 in the sleeved ultrasonic
transducer 40 can provide acoustic performance equivalent to a single metal front driver. .
[0017]
The outer housing 46 can also be made from metals other than aluminum, or non-metallic
materials such as silicon carbide, aluminum oxide, or other advanced ceramics. As used herein,
the term "tip ceramic" refers to a ceramic material having a very high density, with a fine grain
size of 2-3 microns or less than 1 micron and with a porosity near zero. is there. The tissue
structure of the grain is highly uniformed in order to propagate ultrasound signals
simultaneously in all directions. Silicon carbide is a preferred tip ceramic and is made by a
chemical reaction with graphite. Because ceramic has superior ultrasonic vibration energy
conduction characteristics compared to aluminum and other metals, the use of a ceramic
material in the outer housing can enhance acoustic performance, which is a suitable material for
that reason. It can be said.
[0018]
04-05-2019
6
FIG. 9 shows another embodiment different from the configuration of the embodiment of the
present invention shown in FIGS. The transducer 90 has a head mass 92 consisting of an outer
housing 94 and a threaded sleeve 96. The reduced diameter portion 98 of the threaded sleeve 96
extends to the distal end of the outer housing 94. The outer housing 94 is provided with an axial
bore sized to accommodate the reduced diameter portion 98 of the threaded sleeve 96.
Desirably, the outer diameter of the reduced diameter portion 98 of the threaded sleeve 96 is
substantially equal to the inner diameter of the PZTs 14. The vibrational energy generated by the
PZTs 14 is transmitted to the outer housing 96 and then transmitted from the bottom surface
100 of the outer housing to the top surface 102 of the threaded sleeve 96. In other respects, the
transducer 90 is identical to the transducer 40 described above.
[0019]
FIG. 10 shows another embodiment of the present invention in the case of an application using
high frequency. In this ultrasonic transducer 70, two annular PZTs 72 are incorporated in the
center of the stack. Above the PZTs is an annular disk 74 of aluminum oxide, below the PZTs is
an annular disk 76 of silicon carbide, a titanium head mass 78 and a titanium tail. A mass 80 is
provided. The tail mass 80 extends from above with a threaded sleeve 82 which is internally
threaded and extends to the area of the annular hole portion of the stack of transducers. The
head mass 78 extends into the area of the annular hole portion of the stack of transducers, with
an externally threaded member 84 extending from the underside. A sleeve 82 threaded on the
inside of the tail mass 80 threadingly engages a member 84 threaded on the outside of the head
mass 78 to secure the stack of transducers and to combine the head mass and tail mass. And
compress the PZTs 72 and the disks 74, 76 between them.
[0020]
Another embodiment of the present invention relates to the improvement of the ultrasonic
transducer used in the cleaning system shown in FIGS. More specifically, this can be achieved by
manufacturing a container made of quartz or a tip ceramic material and directly bonding a
transducer to the surface of the container. Stacked structures are commonly used in ultrasound
transducers used for cleaning.
[0021]
04-05-2019
7
As a typical transducer, one or more disc-shaped piezoelectric crystals having an annular hole are
used. The piezoelectric crystals are arranged to expand and contract axially in accordance with
the applied electrical signal. One face of the piezoelectric crystal faces the tail mass and the other
face faces the head mass. A piezoelectric screw is compressed between the head mass and the tail
mass by a small screw or bolt. The head mass is fixed to the container, and the vibration
generated from the piezoelectric crystal is transmitted to the container. The tail mass balances
the displacement caused by the expansion and contraction of the piezoelectric crystal. Applicant's
U.S. Patents 5,748,566 and 5,998,908 disclose an improved method for stacked transducer
structures. This is the addition of a resonator made of ceramic material between the piezoelectric
crystal and the head mass.
[0022]
One problem with bonding the transducer to the cleaning container is that problems arise due to
material property mismatches between the container and the material used for the transducer.
The head mass and tail mass are usually made of a metallic material such as aluminum. Such
materials have a higher coefficient of thermal expansion than ceramics such as quartz and silicon
carbide. In the present invention, the structure of the transducer is changed to facilitate adhesion
of the transducer to the container. Typically, one or more transducers are fixed to the inside or
the outside of the container. Usually, several transducers are fixed at the bottom of the washing
vessel. The container is filled with liquid and parts for ultrasonic cleaning, rinsing or other
processing. The transducer is excited by an alternating current.
[0023]
The vibrations generated by the piezoelectric crystal of the transducer are propagated into the
container and transmitted via the liquid to the parts placed in the container.
[0024]
A further alternative embodiment of the present invention is shown as transducer 110 in FIGS.
The components of the transducer 110 are, from the top, comprised of a tail mass 118, an
electrode 120, a ceramic resonator 124, and a head mass 125 which includes a threaded sleeve
04-05-2019
8
126 and an outer housing 128.
[0025]
The bolt 130 is screwed into a threaded hole provided in the threaded sleeve 126 and the
electrode 120, the piezoelectric crystal 122 and the ceramic resonator 124 are compressed
between the tail mass 118 and the head mass 125 Ru. The outer housing 128 is made of silicon
carbide or other ceramic material and is bonded to the flat surface 132 of the threaded sleeve
126. The outer housing is preferably made of a metallic or non-metallic material having a
coefficient of thermal expansion close to that of the container material. Another flat surface 134
of the outer housing 128 is adhesively bonded to the surface of the cleaning container. A
projection 136 at the bottom of the threaded sleeve 126 fits into an axial hole 138 in the outer
housing 128 to facilitate relative positioning of the threaded sleeve and the outer housing. All
parts of the transducer except electrode 120 are axisymmetric in shape. Tail mass 118 and
threaded sleeve 126 are preferably made of aluminum, but if screw strength is a concern, other
non-metallic materials or metallic materials such as titanium may be used. You may make it.
[0026]
Another structure of the transducer 110 is shown in FIG. Transducer 150 has a sleeve 152
extending downwardly to the bottom of outer housing 128 and threaded. By doing this, the area
screwed to the bolt 130 is further increased. The transducer 150 further comprises an insulating
sleeve 154 on the inside diameter side of the PZT 156. Desirably, the outer diameter 158 of the
lower projection 160 of the threaded sleeve 152 is substantially the same as the inner diameter
162 of the PZT 156. With such a structure, vibrational energy generated from the PZT is
efficiently transmitted to the container through the outer housing 128. Further, the inner
diameter of the ceramic resonator 124 may be made equal to the inner diameter of the PZT 156
by extending the insulating sleeve 154 to the top surface of the threaded sleeve 152.
[0027]
One of the advantages of having a configuration such as transducer 110 or 150 is that the head
mass outer housing 128 is made of a metal or non-metallic material such as silicon carbide with
material properties similar to those of the container material. It is something that can be made.
Here, quartz, silicon carbide or other advanced ceramics can be used as the container material.
04-05-2019
9
Silicon carbide is a polycrystalline material. In a ceramic material called silicon carbide, grains
are present, and the size of the grains (crystals) is about 2 to 3 microns. (Directly Sintered) In
addition, there are quartz of different forms, and there are fused quartz and single crystal quartz.
Fused quartz is an amorphous material. (Amorphous or Glassy Material) Generally speaking,
single crystal quartz is one large grain. Such single crystal quartz may have grains of several
inches (in one grain). Grains are not included because fused quartz is amorphous.
[0028]
The thermal expansion coefficients of glass and ceramic are isotropic and not directionally
dependent. The thermal expansion coefficient of single crystal quartz is anisotropic, has direction
dependence and changes with the direction of crystal. Generally, the thermal expansion
coefficient of single crystal quartz is about 15-20 times larger than that of fused silica glass.
Preferred for the wash tank is fused quartz. The coefficient of thermal expansion (in μm / m °
C.) is 0.4 for fused silica, 4.5 for silicon carbide, 17 for stainless steel, 9 for titanium, and 23-24
for aluminum.
[0029]
Thermal expansion mismatch can be extremely reduced by using silicon carbide instead of
aluminum for the portion of the head mass that is bonded to the cleaning vessel. The mismatch
due to the differential thermal expansion of the two adhesively bonded materials induces stress
in the material or boundary layer when the temperature changes. The difference in coefficient of
thermal expansion between aluminum and fused silica is about 60 times, 10 times greater than
that between silicon carbide and fused silica.
[0030]
The transducer 110 or 150 is bonded to the (inner or outer) surface of the container by an epoxy
resin based adhesive "Supreme 10 AOHT". The epoxy resin adhesive is mixed with a ceramic filler
of aluminum oxide (alumina). This adhesive is a heat curing type adhesive having high shear
strength and high peel strength. It also has thermal conductivity and resistance to thermal
cycling. The same adhesive is used to bond the silicon carbide outer housing 128 to the
aluminum threaded sleeves 126,152.
04-05-2019
10
[0031]
The use of silicon carbide in the head mass can provide an ultrasonic transducer that can be
easily bonded to a quartz or ceramic container. And thereby, it becomes easy to efficiently
transmit ultrasonic vibration from the transducer to parts etc. in the container.
[0032]
From the above discussion, it is apparent that the invention disclosed herein provides a novel and
effective sleeved ultrasonic transducer. The discussion above is merely representative of
exemplary methods and embodiments of the present invention. Those skilled in the art can
implement specific embodiments other than those described herein without departing from the
essential features and basic ideas of the present invention. Accordingly, the invention disclosed
herein is illustrative and not intended to limit the scope of the invention. The scope of the
invention is defined by the appended claims.
[0033]
FIG. 1 is a cross-sectional view of a prior art ultrasonic transducer having a head mass made of a
single metallic material. FIG. 2 shows a cross-sectional view of another prior art ultrasonic
transducer having two head masses made of two metallic materials. FIG. 3 shows a first
embodiment of an ultrasonic transducer according to the present invention, showing a crosssectional view of a threaded sleeve of the head mass. FIG. 4 is a cross-sectional view of the outer
housing of the head mass, a first embodiment of an ultrasonic transducer according to the
present invention. FIG. 5 is a cross-sectional view of a sleeved ultrasonic transducer according to
the present invention, using the titanium sleeve shown in FIG. 3 and the aluminum housing
shown in FIG. 6 is a side view of a sleeved ultrasound transducer of the transducer shown in FIG.
FIG. 7 shows an impedance-frequency diagram of a transducer having two front drivers of
aluminum and titanium shown in FIG. FIG. 8 shows an impedance-frequency diagram of a first
embodiment of a sleeved ultrasonic transducer according to the present invention. FIG. 9 is a
cross-sectional view of another embodiment of a sleeved ultrasonic transducer according to the
present invention, similar to the transducer shown in FIGS. 3-6. FIG. 10 shows still another
embodiment of a sleeved ultrasonic transducer according to the present invention. FIG. 11 is a
cross-sectional view of yet another embodiment of a sleeved ultrasonic transducer according to
the present invention. FIG. 12 shows a side view of the transducer shown in FIG. FIG. 13 is a
04-05-2019
11
cross-sectional view of yet another embodiment of a sleeved ultrasonic transducer according to
the present invention.
Explanation of sign
[0034]
40, 70 Ultrasonic Transducer 14, 122 Piezoelectric Crystal 80, 118 Tail Mass 42, 78, 92, 125
Head Mass 22, 130 Volt 44, 82, 96, 126, 152 Sleeve 46, 94, 128 Outer Housing 52 Counter
Bore hole
04-05-2019
12
Документ
Категория
Без категории
Просмотров
0
Размер файла
24 Кб
Теги
jp2008236781
1/--страниц
Пожаловаться на содержимое документа